Anti-induction device for telephonic circuits



(No Model.) I I H. VAN HOEVENBERGH.

ANTI INDUCTION DEVICE FOR TELEPHONIO CIRCUITS. No. 308.019.

Patented Nov. 11, 1884.

UNITED STATES PATENT OFFICEo HENRY VAN HOEVENBERGH, OF ELIZABETH, NEV J ERSEY.

ANTl-INDUCTION DEVICE FOR TELEPHONIC C IRCUITS.

SPECIFICATION forming partof Letters Patent No. 308,019; dated November 11,1884.

Application filed April 52, 198-1.

To all whom it may concern.-

Be it known that I, HENRY VAN HoEvEN- BERGI-I, a citizen of the United States, residing in Elizabeth, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Anti'lnduc tion Devices forTelephonic Gircuits,of which the following is a specification.

My invention relates to the organization of telephone-circuits; and the object of the invention is to provide means for obviating the detrimental effects due to static or induced charges.

Vhen telephone lines are constructed of considerable length, it is found that the variations in the strength of the currents transmitted, or the undulations in the same, which are relied upon for actuating the receivinginstruments, become so far reduced by reason of the static charges that the effects derived therefrom are very much less than thosepro duced when the transmission is over a short line. 7

Various means have been adopted for preventing the establishment of static charge and for overcoming the detrimental effects of the same. Especially is this true in the organization of telegraphic circuits. It has, for instance, been customary to employ for this purpose induction-coils, condensers located in compensating lines, and also peculiar arrangements of telegraphic conductors.

My invention consists in inserting in a telephonic conductor, at or near its respective ends, a condenser or its equivalent, which is so organized that the line-currents are forced to traverse the entire length of one of the con denser-plates instead of acting merely to electrically charge the same, as in the usual form of condenser. The remaining plate or arm of the condenser is connected with the earth. This organization is especially useful in in stances when the conductors in the immediate vicinity of the stations are required to pass under ground, while the remaining portion of the line is aerial. The condensers may then be sections of so-called lead cable. The lead cable consists of one or more insulated conductors inclosed within a lead pipe or tube. The pipe or tube then constitutes one arm of the condenser, while the conductor in- (No model.)

closed within the same constitutes the other arm. The currents to and from the main line will, therefore, be forced to traverse the entire length of the last-named arm of the condenser, while the remaining armthat is to say, the pipeis in actual contact with the earth.

From such' organizations as above-mentioned I have obtained very perfect and satisfactory results.

The accompanying drawing illustrates the invention as applied to the construction of aerial lines which it is desired to connect with sections of underground cables.

Referring to the drawing, 3' and M represent sections of an underground cable. The cable may be constructed with any desired number of conductors, a, which are surrounded by or embedded in insulating material, a. Surrounding the entire group of conductors is an inclosing lead or other metallic shield, K. The sections M and M are designed to be placed under ground, and they have their outer coverings, K, therefore in connection with the earth. One or more of the conductors a in each cable are connected at one ton minal with the main line and at the other terminal with the conductor L including the telephonic instruments H. The length of the conductor aywhich is thus included in circuit and constitutes one arm of the condenser, is preferably, in some degree, proportionate to the length of the aerial conductor L. Thus, if the conductor L is comparatively short, then it is not necessary to employ cable sections of as great length as are necessary for very long aerial lines L.

in another application filed by me April 12, No. 127,692, is shown and described an organization in some respects similar to that herein described; andIdonot, therefore, herein claim anything shown, described, and claimed in that application and not specifically claimed herein.

I claim as my invention- 1. The combination, substantially as hereinbefore set forth, of a telephonic main line and sections of underground metallic-covered cables included in the circuit of said mainline at or near its respective terminals, substantially as described.

ICO

2. The combination, substantially as hereinbefore set forth, with telephonic transmitting and receiving instruments, of a telephonic main line and a condenser consisting of a metallic-covered cable at or near each terminal of said main line, one arm of each of which condensers is included in the circuit of said main line in series, While the remaining arms are connected directly with the earth.

3. The combination, substantially as hereinbeiore set forth, of a telephonic main line and a condenser consisting of a metallic-covcred cable or conductor inserted at or near the respective terminals of the same, one arm of each condenser being included iii the circuit of the main line, While the other is connected directly with the earth.

In testimony whereof I have hereunto subscribed my name this 1st day of April, A. l). 1884.

HENRY VAN HOE'VENBERGl-L Witnesses:

DANL. XV. EDG'ECOMB, CHARLES A. TERRY, 

